Typically, the attachment of such miscellaneous function payloads as, for example, antenna arrays, guidance systems, rocket pods, and the like, to the exterior of an aircraft, it is accomplished by means of structural and functional provisions incorporated into the original design of the aircraft or via subsequent structural modifications to a completed aircraft. Such external attachment arrangements create special problems in the design and construction of the fuselage adjacent the external attachment points in that the payload must be properly supported so as to withstand its own weight as well as airloads and winds to which it may be subjected during the operation of the aircraft.
When greater performance is required of the aircraft, as is presently the case, and an external payload is included, those above-noted considerations become compounded. External payloads make it necessary to reinforce the adjacent stationary structure to assure its integrity during flight, and hence add weight to the aircraft. Moreover, designing-in such provisions, or adding them on through modifications, limits payloads to only those which are compatible with the original design limitations while imposing on-going weight and aerodynamic drag penalties even when the external payload is not in use .
In addition to the aforementioned considerations, pressurization of the aircraft interior, during high altitude flights, presents further difficulties due to leakage through structural and functional load paths which pass through the pressure vessel of the aircraft fuselage.